This mysterious underground cave in Shropshire dates back to the 18th or 19th century.

A red sandstone freestanding monolith rises out of the sea in northern Scotland.

His "Lionheart" is entombed separately from the rest of his body.

An unfinished complex built for children from around the world sits abandoned on the Black Sea coastline.

A tree that defies gravity grows in an ancient ruin.

This splendid tomb may look fantastic, but there's nothing in it...

The man who was president for only one day and spent most of it asleep.

A secret hatch containing two parchments was discovered in this statue over 40 years after its installation.

The mysterious wonder of an underground waterfall is illuminated by multicolored lights.

Two awe-inspiring globes from the reign of the Sun King hang from the ceiling of France's national library.

Where scientists keep miles of very valuable ice from Antarctica and Greenland from melting.

A 19th century library favored by Edgar Allan Poe and H.P. Lovecraft, known by locals as "the Ath."

This valley of hot springs and boiling mud pots is home to the record-holding "Geysir," which originated the English word.

Some of the best-preserved specimens of the monumental medieval tombstones found throughout Bosnia and Herzegovina.

A fairytale-like medieval church perched atop a rocky cliff on Italy's "Coast of the Gods."

Just another ancient, mysterious Irish stone circle.

A little known Colombian theme park of giant curiosities.

A winding, blood-red tunnel of hardened lava navigable by foot.

The oldest place in Hartford is a cemetery with thousands of bodies stacked beneath the grass.

The former home of a railway legend and the site of a gigantic labyrinth.

If a glacial river suddenly diving into a sheer chasm via a dramatic, multi-stage waterfall isn't peak Iceland, it's certainly close.

A fairytale Gothic castle steeped in Nazi treasure conspiracy theories.

Sacked by Vikings, blessed by William the Conqueror, dealt a fatal blow during the French Revolution—these ruins have seen it all.

In the town of Åtvidaberg, the midday sun sets off a loud cannon boom.